Silk fibroin-based biopolymer films can be patterned on the micro- and nano-scale using a soft lithography techniques in which silk fibroin is cast on a photonic planar lattice. This casting process, however, takes 12 to 36 hours, which may not be convenient for rapidly producing multiple devices. In addition, although the soft lithography casting technique is effective, it may impart some artifacts to the film, such as uneven edges from mechanical lift-off or extra depth in the reproduced features from the drying process.
Nanoimprinting is an alternative high-throughput lithography technique for fabricating micro-, submicro- and nanometer-scale patterns. In this method, a mold is pressed onto a thermoplastic material heated above its glass transition temperature, and the softened material conforms to the mold due to applied pressure. There remains need for techniques to fabricate nanopatterned biopolymer films with improved resolution and high throughput, particularly at physiological and room temperatures, for use in biomedical and optical devices applications that incorporate cells, enzymes, or other heat-labile substances.